Wood-Boring Insects in Buildings

Look for signs of activity, not just holes

A beetle makes an exit hole when it leaves the timber. That hole remains afterwards, whether the infestation is still active or ended many years ago.

Fresh activity is more likely where there is new frass, recent-looking holes, live insects or continuing damage. The exact evidence varies with species.

Not every part of the timber is attacked equally

Some wood-boring insects mainly attack sapwood rather than the denser heartwood. A timber can therefore look heavily perforated at the surface while retaining substantial strength deeper inside.

That is one reason wholesale replacement based only on visible holes can be excessive.

Moisture can influence insect attack

Some beetles favour timber that has already been damp or affected by fungal decay. Correcting a moisture problem can therefore be part of controlling the conditions that made the timber attractive in the first place.

Identify before treating

The insect species, whether it is active and the extent of structural damage should be established before deciding on treatment. In historic buildings, unnecessary chemical treatment can damage other interests such as bats as well as disturbing original fabric.